Louver system with hinged blades

ABSTRACT

In a spacecraft of the type having a surface, a plurality of louver means mounted onto said surface for rotation about axes parallel to one another and to said surface, and thermally responsive actuator means for controlling the angular displacement of said louver means about their respective axes, the improvement wherein each louver means is comprised of a plurality of substantially parallel panels hinged with one another substantially about one of their longitudinal edges, a first panel being further mounted to rotate about an axis parallel and adjacent to said surface, and the outer panel being attached at its outer longitudinal edge to a driving element in turn connected to said actuator means, the latter being adapted to move said driving element linearly in the direction perpendicular to said surface, thereby causing the respective angular positions of the panels to vary depending on the sensed temperature. The actuator means can advantageously be a device common to all louver panels.

ilnited States Patent [191 .1 anes [4 1 Mar. 25, 1975 1 LOUVER SYSTEM WITH HINGED BLADES [75] Inventor: Manfred .lanes,Voorschoten,

Netherlands [73] Assignee: Organisation Europeenne de Recherches Spatiales, Neuilly-sur-Seine, France [22] Filed: June 26, 1973 [21] Appl. No.: 373,624

[52] U.S. Cl 160/1, 49/25, 49/82,

244/163 [51] Int. Cl E05f 17/00 [58] [Field of Search 160/1, 2, 5, 6, 218, 220,

160/229, 231, 236; 49/1, 25, 74, 82; 244/1 SC, 1 SS, 158,162,163

FOREIGN PATENTS OR APPLICATIONS United Kingdom 49/77 Primary Examiner-Mervin Stein [57] ABSTRACT In a spacecraft of the type having; a surface, a plurality of louver means mounted onto said surface for rotation about axes parallel to one another and to said surface, and thermally responsive actuator means for controlling the angular displacement of said louver means about their respective axes, the improvement wherein-each louver means is comprised of a plurality of substantially parallel panels hinged with one another substantially about one of their longitudinal edges, a first panel being further mounted to rotate about an axis parallel and adjacent to said surface, and the outer panel being attached at its outer longitudinal edge to a driving element in turn connected to said actuator means, the latter being adapted to move said driving element linearly in the direction perpendicular to said surface, thereby causing the respective angular positions of the panels to vary depending on the sensed temperature. The actuator means can advantageously be a device common to all louver panels.

3 Claims, 3 Drawing Figures The present invention relates to an improved louver system for use on spacecrafts and space vehicles.

Louver systems are used to control the skin temperature of spacecrafts and space vehcles during their mission and to maintain it within prescribed limits. Such systems usually comprise rotatable panels mounted in parallel relationship onto the outer surface of the vehicle and operated by suitable temperature-sensitive actuators which cause the panels to pivot depending on the sensed temperature so as to vary the thermal radiation from said outer surface towards the environmental space.

Typically, the panels are comprised of two substantially parallel thin metallic blades that are spaced apart so as not to be in thermal contact with each other. The actuators comprise devices well known in the art. A usual form includes a bimetallic spiral spring associated with each louver panel with one end fixed to said axis and its other end attached to the panel support means I or the outer surface of the vehicle. Such a spiral spring expands open or contracts depending on the sensed' temperature, thereby causing the panel axis to rotate, and consequently, the panel to pivot. The angular position of the panel thus depends on the spring temperature which in turn is representative of the temperature of the outer surface of the vehicle. When said tempera ture increases, either by radiation or heat conduction, from parts inside of the vehicle, the panels are caused to rotate so as to increase the opening angle thereof relative to the vehicles outer surface, thereby enhancing thermal radiation of the outer surface towards the environmental space. On the other hand, when the temperature of the outer surface of the vehicle decreases, the panels are caused to rotate so as to decrease their opening angle relative to said outer surface, thereby reducing the thermal radiation of said outer surface towards the environmental space.

The length and width of the louver system are determined by the area of the surface, the temperature of which is to be controlled. The total height of the louver system onto the outer surface of the vehicle is determined by the number of louver panels. The product of the surfacearea ofa panel by the number of panels has to be equal at least to the area of the outer surface of the vehicle. When the system is completely open, i.e., when the panels are inan orthogonal position relative to the outer surface of the vehicle, a sufficient clearance space should be maintained between the outer surface and the location of the panel pivots such as to enable the louver panels to rotate. The necessary displacement of the panels from their closed position to their completely open position is a quarter ofa revolution.

A known system as described above in fact comprises a number of independent subunits relative to one another, each subunit being comprised of a louver panel and the actuatorassociated thereto. In such a system, care should be taken to have the louver panels, their angular movement and the friction occurring between the panel axis and the pivots to be accurately balanced, and also to have every actuator accurately calibrated. In addition, each actuator should be carefully thermally isolated in order to make it insensitive to external influences so that its temperature reflects as closely as possible that of the outer surface of the vehicle.

Moreover, such a known louver system also has a limited angular control range. In effect, the maximum opening angle is and this angle value cannot be increased in this type of louver system.

It is an object of the invention to provide a louver system wherein the maximum opening angle is substantially greater than that of the known devices.

Another object ofthe invention is to provide a louver system wherein the louvers are actuated by a common actuator.

Another object of the invention is to provide a louver system wherein the louvers and the actuator are two independent subunits. In the drawings:

FIG. 1 is a schematic perspective view of a portion of an embodiment of the invention;

FIG. 2 is a cross-sectional view showing two louvers in partially open position;

FIG. 3 is a schematic cross-sectional view ofan illustrative embodiment of the actuator.

Referring to FIG. 1 there is schematically shown in perspective view a portion of the outer surface 1 of a spacecraft, e.g., a satellite, onto which is mounted an illustrative embodiment of the louver system of the invention. This louver system comprises a plurality of louvers 10 mounted onto surface 1 for rotation about parallel axes. Three louvers 10 are shown, each louver illustratively comprising two panels 2 and 3 which are hinged with one another about one of their longitudinal edges: hinge joints 4 and 5 are provided at the ends of said longitudinal edges. Panel 2 is also hinged with the outer surface 1 at hinge joints 6 and 7 provided at the ends of its longitudinal edge adjacent the surface 1.

The panel Width is chosen so that when the system is completely closed, i.e. when panels 2 and 3 are folded up so as to be substantially parallel to each other and to outer surface 1, the area of the outer surface I is entirely covered. Maximum radiation is obtained when the system is completely open, i.e., when the panels all extend perpendicularly to the outer surface I. Between these two extreme positions, all transitions are possible depending on the relative angular positions of the panels. As can be seen on FIG. 2, the radiation from the system towards space can be emitted from the outer surface 1 in any direction between 0 and as a result of the reflections on the panels as shown by the dashed lines. This foldable system thus provides a range of opening angles which is twice that of the known devices.

The outer panels 3 are attached to one or more metal rods 8 running across the system and connected to an actuator represented by block 9. The actuator is a device responsive to a signalrepresenting the temperature of the outer surface 1 and adapted to move rod 8 linearly along a direction perpendicular to the outer surface 1, as indicated by double arrow D. When said temperature increases, rod 8 is caused to move upwards as seen in FIGS. 1 and 2, thereby driving panels 3 to pivot upwardly; panels 3 in turn drive panels 2 to pivot upwardly so that the opening angle is increased.

When said temperature decreases, rod 8 is caused to,

move downwards as seen in FIGS. 1 and 2, thereby driving panels 3 and 2 to pivot downwardly and to re duce their opening angle. The actuator has only to actuate rod 8 linearly and it can thus be a simpler device than the conventional actuator means used in the art which have to provide a rotating actuation movement.

In this system of the invention, the louver mechanism and the actuator are two independent subunits and the actuator can be a common device for all louver panels. This constructional separation results in a great advantage from the standpoint of manufacturing and the standpoint of design flexibility. That is, the louver sys tem can be chosen in accordance with the structure requirements irrespective of the temperature range of interest. The actuator system has to be chosen to meet said temperature range and it can be simply coupled to the louver system.

The actuator system should comprise temperature sensor means with low thermal capability (e.g., a thermistor or thermocouple), an actuating mechanism and a power supply for said actuating mechanism. The temperature sensor means is adpated to sense the temperature of the outer surface of the vehicle and to apply a control signal to the actuating mechanism. The latter in turn is drivingly coupled to the louver panels to move same depending on the sensed temperature. Various embodiments can be arranged. A typical embodiment can comprise a Wheatstone bridge arrangement as used to control a chart recorder. The temperature sensor is connected in a leg of the bridge. The bridge is brought out of balance when a variation occurs in the temperature of the outer surface of the vehicle as sensed by the temperature sensor. Electric power is then fed to an electric motor which varies the compensating resistance of the bridge to restore balance thereof. The power delivered by the motor then is used to drive the louver system. This emobidment is satisfactory as regards its response time but it requires a motor which increases the weight of the system.

Another illustrative embodiment is depicted in FIG. 3. This embodiment essentially comprises a bellow 31 fixed between two plates 32 and 33, and an electric heater means 34 fed by a temperature sensor (not shown) adapted to sense the temperature of the outer surface of the vehicle and to produce a current in response thereto. The volume inside the bellow is filled with a gas. the pressure of which corresponds to the counterpressure of the bellow and the louvers. When the bellow 31 is completely isolated from the environment, e.g., when it is surrounded by an insulating material represented at 35, the system thermally represents an adiabatic system. The heating current I through heater means 34, which is representative of the temperature of the outer surface of the vehicle, increases the gas temperature and hence the pressure thereof, and plate 33 is moved upwards in the direction indicated by arrow P on FIG. 3. The rod 8 driving the louvers as described above is connected to shaft 36 so that plate 33 moving upwards causes the louvers to pivot open. When the bellow 31 partially leaves the space surrounded by the insulating material 35 as shown in FIG. 3, it is allowed to radiate in the environmental space and the system thereby is changed from an adiabatic to an isothermal system. The heating power supply is regulated so that the increase of the gas volume due to the temperature increase of the outer surface ofthe vehicle is sufficient that the area increase ofthe bellow surface permits heat power to be radiated from said bellow surface.

Variations to the described embodiment can obviously be devised by those skilled in the art without departing from the scope of the invention. For instance. the gas enclosed within the bellow can be heated from outside of the bellow as well. Also it is to be understood that the number of louver panels is nowise limited to two as in, the illustrative embodiment described above.

What is claimed is:

1. In a spacecraft of the type having a surface, a plurality of louver means mounted onto said surface for rotation about axes parallel to one another and to said surface, and thermally responsive actuator means for controlling the angular displacement of said louver means about their respective axes, the improvement wherein each louver means is comprised ofat least two substantially parallel panels hinged with one another substantially about one of their longitudinal edges, the panels of each louver means being mounted with respect to each other, a first panel of each louver means being further mounted to rotate about an axis parallel and adjacent to said surface, and the outer panel of each louver means being attached at its outer longitudinal edge to a driving element in turn connected to said actuator means, the actuator means comprising means for moving said driving element linearly in a direction perpendicular to said surface, thereby causing the respective angular positions of the panels to vary depending on the sensed temperature. I

2. The spacecraft of claim 1 wherein said actuator means is comprised of a device commonly connected to all louver panels.

3. The spacecraft of claim 2 wherein said actuator means comprises a temperature sensor element means for providing an electric current representing the temperature of said surface, bellow means mounted between a fixed plate and a movable plate being linearly displaceable in a direction perpendicular to said surface, said movable plate being drivingly connected to the outer panels of said louver means, the inside volume of said bellow means being filled with a gas at a predetermined pressure, and electric heater means inside said gas filled bellows means and fed by the current from said temperature sensor element to cause the gas pressure to vary depending on the sensed temperature. 

1. In a spacecraft of the type having a surface, a plurality of louver means mounted onto said surface for rotation about axes parallel to one another and to said surface, and thermally responsive actuator means for controlling the angular displacement of said louver means about their respective axes, the improvement wherein each louver means is comprised of at least two substantially parallel panels hinged with one another substantially about one of their longitudinal edges, the panels of each louver means being mounted with respect to each other, a first panel of each louver means being further mounted to rotate about an axis parallel and adjacent to said surface, and the outer panel of each louver means being attached at its outer longitudinal edge to a driving element in turn connected to said actuator means, the actuator means comprising means for moving said driving element linearly in a direction perpendicular to said surface, thereby causing the respective angular positions of the panels to vary depending on the sensed temperature.
 2. The spacecraft of claim 1 wherein said actuator means is comprised of a device commonly connected to all louver panels.
 3. The spacecraft of claim 2 wherein said actuator means comprises a temperature sensor element means for providing an electric current representing the temperature of said surface, bellow means mounted between a fixed plate and a movable plate being linearly displaceable in a direction perpendicular to said surface, said movable plate being drivingly connected to the outer panels of said louver means, the inside volume of said bellow means being filled with a gas at a predetermined pressure, and electric heater means inside said gas filled bellows means and fed by the current from said temperature sensor element to cause the gas pressure to vary depending on the sensed temperature. 